It has long been known that absorbent articles such as conventional taped diapers, pull-on diapers, training pants, sanitary napkins, pantiliners, incontinence briefs, and the like, offer the benefit of receiving and containing urine and/or other bodily exudates. To effectively contain exudates, the articles should provide a snug fit around the waist and legs of a wearer. Articles such as conventional diapers generally include a front and a rear waist section releasably connected by a fastening means. Application of a conventional diaper is usually performed by a caregiver with the wearer in a supine position. Such diapers may allow for easy application by the caregiver but generally make self-application by the wearer very difficult. Furthermore, conventional diapers may be difficult to apply when the wearer is in a standing position.
Disposable pull-on diapers were developed, in part, to address the problem associated with conventional diapers such as difficulties related to self-application and standing application. Pull-on diapers are designed to effectively contain exudates while allowing for self-application. Pull-on diapers generally include a front waist region, a back waist region, and a crotch region therebetween. The front waist region and back waist region may be attached to form a waist opening and pair of leg openings. Generally, pull-on diapers are manufactured in a prejoined configuration such that the front and rear waist sections do not need to be attached by a wearer or caregiver prior to wear. In one particular facet, pull-on diapers have become popular for use on children who are able to walk and who may be engaged in toilet training. Pull-on diapers may serve as an intermediary product for the child between a conventional diaper and underwear. The pull-on provides a milestone for the child who may be toilet training and developing independence from the caregiver. However, to be an effective advance over a conventional diaper, the pull-on should not only allow for self-application but should also provide a mechanism for easier self-application.
Unfortunately, current pull-on diapers may be difficult for self-application by a child. Many pull-on diapers have elastic elements in the portion of the pull-on diaper that encircles the waist of the child during wear. The elastic elements allow the pull-on diaper to achieve a snug, conforming fit about the waist of the child. The elastic elements also allow the pull-on diaper to fit a range of shapes and sizes thereby enabling the pull-on diaper to exhibit a degree of customized fit. While the elastic elements are beneficial once applied, the elastic elements may inhibit the process of application and, particularly, self-application. During application, the waist opening of a pull-on diaper may be enlarged from its relaxed dimensions. Enlargement of the waist opening is often necessary given the geometry of a child wearer. As the pull-on diaper is pulled from a child's feet to the child's buttocks, the circumference of the child generally increases. Ideally, the pull-on diaper will maintain an enlarged waist opening during the application process. Specifically, throughout the application process, the waist opening circumference should stay larger than the circumference of the child over which the waist opening must pass. Child studies have shown that self-application of a garment (e.g., underwear or pull-on diaper) may take anywhere from about 12 seconds to about 2 minutes depending upon factors such as the child's size, dexterity, strength, and attention span. Typically, self-application may take from about 15 seconds to about 30 seconds.
However, existing pull-on diapers do not maintain an enlarged waist opening once elongated. Elastic elements within the pull-on diaper may exert a force that constricts the waist opening. The child or caregiver may need to exert a lateral force either to increase the size of the waist opening of the pull-on diaper or to maintain the size of the waist opening. The need to exert a lateral force may exist if the waist opening of the pull-on diaper constricts to a circumference smaller than a circumference of the child over which the diaper must pass at some given time of application. For example, the region of the buttocks typically is the greatest circumference over which pull-on diaper must pass. A lateral force may need to be applied to the pull-on diaper if the diaper's waist opening is smaller than the circumference around the child's buttocks when the diaper passes over the buttocks during application.
It should also be appreciated that any constrictive force pressing against the body of the wearer results in friction that must be overcome in the application process. If the pull-on diaper is in contact with wearer's body as the diaper is applied, the waist opening must continue to expand which results in increased strain upon the elastic elements. Increased strain often results in increased normal forces which further increases the friction that must be overcome by the child. Given a child's limited dexterity and strength, an increase in friction may make successful application of the pull-on diaper impossible.
Furthermore, as the pull-on diaper is advanced up the legs, the anatomy of the wearer may serve as a geometric barrier to application. The buttocks may serve as barrier that can catch the waist edge of the pull-on diaper and effectively prevent further upward advancement of the pull-on diaper. The waist opening may need to be enlarged to a circumference generally greater than that of the buttocks. The forces exhibited by elastic elements in current products may make enlargement of the waist circumference difficult for the applicator and impossible for a child.
Another factor making application of a pull-on diaper difficult is waist opening deformation. Ideally, the shape of waist opening of the pull-on diaper should mirror the shape of the wearer and, particularly the shape of the child at the point of greatest circumference. Generally, a circular or elliptical (e.g., an ellipse having an aspect ratio of approximately 1:1 to 1:2) shaped waist opening are preferred. However, if the waist opening must be enlarged, this preferred waist opening shape can be deformed. For example, in enlarging the waist opening, the applicator typically grasps the pull-on diaper at two points evenly spaced around the waist edge. Applying a lateral force creates a line of force traveling between the grasp points. As the waist opening elongates along this line of force, the waist opening may draw in or neck in a direction perpendicular to the lateral line of force. Since the applicator often grasps the sides of the pull-on diaper that are proximate to the hips of the wearer, the pull-on diaper may neck between the front and the back of the diaper. Necking of the diaper in the front and the back may further hinder application since the waist opening is being necked in at the point where the wearer's geometry protrudes, the buttocks.
Even if a caregiver wishes to aid the wearer in self-application, current pull-on diapers may frustrate such efforts. A caregiver may enlarge the size of the waist opening of a pull-on diaper before providing the pull-on diaper to the wearer for application. Ideally, the caregiver may stretch the waist opening to a circumference greater than that of the lower torso of the wearer. However, if the elongating force is not maintained, the pull-on diaper will typically “snap back” to substantially its original, relaxed dimension due to the force exerted by the elongated elastic elements. The elastic elements of current pull-on diaper construction are aggressive in that they contract rapidly and exert relatively high forces. As a result, if the pull-on diaper is expanded by a caregiver and then provided to a child, the child is left with a pull-on diaper that may require application of a continuous elongating force or else the product returns to its original, relaxed dimension.
In light of the problems described above, it is desirable to provide a disposable pull-on diaper that is tailored for ease of application and, especially, ease of self-application by a child. It would be beneficial to provide a disposable pull-on diaper having a waist circumference that retains its elongated state for some period of time after release of the elongating force. It would be particularly beneficial if this period of time approximates the average time necessary for the application process. It would also be beneficial to provide a disposable pull-on diaper requiring only minimal force to maintain elongation or to re-elongate the pull-on diaper. It would also be beneficial if the pull-on diaper exerted a gradual increase in force upon recovery.